A connection of hydraulic lines may be implemented by way of various constructive solutions. For example, a seal having axially sealing annular seals is known. A further possibility exists in the use of connecting bushes having radially sealing annular seals. In this embodiment, annular seals are usually inserted into radial grooves of the connecting bushes, wherein the annular seals are in most cases supported by annular supports, as will be described hereunder.
In the event of an intensely pulsating pressure, the known connecting methods cannot ensure a sealing function or can only be fitted in a laborious manner. The first applies to axially sealing annular seals; they cannot ensure a sealing function in the event of high or intensely pulsating pressures. It has proven unfavorable in the case of connecting bushes with radially sealing annular seals that the latter can be fitted only in a laborious manner. The sealing faces of the pressure lines may be easily damaged during fitting. This caused by the hard bush easily being able to contact the sealing faces of the pressure lines. In order for the connecting bush to be able to be inserted without causing damage, a gap is provided between said bush and the hydraulic line. However, an annular seal may be extruded into this gap. Extrusion means that an annular seal is urged into a gap on the low-pressure side and is thus destroyed, on account of which a sealing function of the connection is no longer ensured. In order to avoid extruding the annular seal, as well as the annular seals, annular supports are additionally inserted into the annular grooves in the case of the connecting bushes of the prior art, which annular supports at least reduce the respective gap in the region around the groove and thus prevent extruding. However, it has proven disadvantageous that an additional fitting effort is required for fitting the annular supports. It is furthermore disadvantageous that the annular supports may be forgotten during fitting or be incorrectly fitted. On account of the mentioned disadvantages, connecting bushes having axially sealing annular seals are to some extent susceptible to defects during fitting, resulting in a susceptibility to defects of the connection during operation.
Similar disadvantages also present themselves in hydraulic plugs of the prior art. Hydraulic plugs are inserted into open hydraulic lines and close the latter. In a comparable manner to hydraulic connecting bushes, hydraulic plugs are also made of a cylindrical main body having at least one annular groove which encircles the external sleeve face thereof and in which in each case also one annular seal is inserted. In the prior art, annular supports are also inserted in the case of hydraulic plugs on the low-pressure side ahead of the annular seal, preventing extruding of the annular seal. As opposed to the cylindrical main body of a hydraulic connecting bush, the cylindrical main body of a hydraulic plug is closed on one end side in order to avoid leakage of the hydraulic medium. Hydraulic plugs must be fixed in the axial direction in relation to the hydraulic line, so as to fix said hydraulic plugs also in the event of the hydraulic line being impinged with internal pressure.